The present invention relates to a mode discriminating method and apparatus for controlling the switching of operating modes of a tape recorder and other various mechanisms which selectively perform diverse functions, and more particularly, to a mode discriminating method and apparatus which discriminates an operating mode to be switched by adopting as one factor the rotating direction of a driving source (motor) driven during mode switching.
For instance, a video tape cassette recorder (VCR) for recording/reproducing information with a video cassette tape includes a cassette loading mechanism for loading a cassette and a deck mechanism for driving a tape of the loaded cassette. In a specific video tape cassette recorder, when a cassette is inserted, the cassette is conveyed to a deck mechanism of the recorder from the insertion slot. With the cassette seated on the deck mechanism, the tape is drawn out from the cassette and then loaded onto a recording/reproducing head drum. Thereafter, an operation such as recording or playback, which is selected by a user, is carried out.
In such a VCR, a conventional deck mechanism for switching operating modes is, as shown in FIG. 1, equipped with a motor 1 for generating power to switch operating modes, a master gear 2 rotatively driven by motor 1, a main slide 3 connected to move in accordance with the rotation of master gear 2, and a rotary mode detecting switch 4 installed on the same axis as that of master gear 2. Here, master gear 2 and main slide 3 interlock with other unshown gears and levers according to the rotation of master gear 2 and the movement of main slide 3 so as to switch the operating state, i.e., an operating mode of the mechanism. Mode detecting switch 4 detects a switched operating mode according to the rotating position of master gear 2, as disclosed in U.S. patent application Ser. No. 08/087,332 filed on Jul. 8, 1993.
Mode detecting switch 4, as shown in FIG. 1, bears a conductive pattern 5 formed on a plurality of concentric circles, a contact slider 6 which is provided on the conductive pattern and rotates with master gear 2 for slidable contact with the pattern, and a plurality of terminals 7. Mode detecting switch 4 outputs a plurality of switch signals indicative of an operating mode of the mechanism from terminals 7 and therefore provides information on the operating mode to microprocessor 8 for controlling the whole mechanism including motor 1. Microprocessor 8 is connected to key input 9 which is manipulated by a user so as to operate motor 1 according to the signal of the key input, and to stop the motor once the mechanism has been switched to the selected mode. As discussed above, in the conventional mechanism, rotary mode detecting switch 4 is used to detect and discriminate the operating mode of the deck mechanism with the plurality of switching signals so as to control the switching of operating modes.
In general, the number of modes detectable by a switching device is 2.sup.n (where n is an integer representing the number of switching elements). For example, eight (2.sup.3) modes can be detected with three switching elements. A switching element is a switching contact. The individual concentric circles in conductive pattern 5 are the switching elements, and there may be more than one switching element on each concentric circle. The mode detecting switch 4 requires at least four conductive patterns including a common electrode and accordingly, the corresponding number of terminals.
Thus, the detection capability of the conventional mode detecting switch 4 has a limit in practice. For a multifunctional deck mechanism, many conductive patterns and terminals are required, which complicates its structure accordingly. The rate of defective products is higher due to the increased number of switching elements, resulting in numerous errors in mode detection.
In order to detect more modes, the addition of other switching elements as well as increasing the amount of conductive patterns can be considered. However, this is undesirable because the addition of switching elements raises production cost and makes their arrangement more difficult.